1. Field of the Invention
The present invention relates.
2. Description of Related Art
FIG. 1 shows a traditional varistor. The varistor 10 comprises a surge absorber 11, two electrodes 13 disposed on the opposite sides of the absorber 11, and two leads 15. In FIG. 1(a), only one of the electrodes 13 is illustrated, and the leads 15, usually made from tinned copper wires, are welded on the respective electrodes 13. In FIG. 1(b), the absorber 11 is embedded with a packaging resin 17 for damp-proof and insulation effects. The packaging resin 17 is usually epoxy resin.
For operation, the surge absorber 11 may protect the power circuit with grain boundary thereof. However, the surge absorber 11 very possibly reaches a high temperature when the surge absorber 11 is overloaded or ineffective, and therefore the outside packaging resin 17 would burn as flammability thereof. In addition, a flame from the burned packaging resin may damage to surrounding equipment close to the surge absorber 11.